An air filter consisting of a 120mm PC fan, a random HEPA filter, and some 3D printed parts.
To open the .scad files, install OpenSCAD. If you want to use a different fan or filter, you can customize the dimensions of the 3D printed parts easily (Window->Customizer in OpenSCAD), no need for editing the SCAD code! Then export (F6 and then F7) to STL, slice, and print them :)
To attach the fan, I used M4*10mm screws, but M2/M3 and/or other lengths should also work. To the bottom plate I stuck six rubber feet, but they aren't absolutely necessary.
